1978 Johnson 175, 200, 235 HP Outboard Service Manual, Page 171Get this manual
DESCRIPTION The power trim unit consists of manifold that contains all valving, oil reservoir, oil pump, electric motor, and hydraulic trim cylindersAttached to the manifold is the combination hydraulic tilt cylinder and shock absorberThe entire assembly is attached to and contained completely between the stern bracketsThe tilt cylinder is connected to the manifold and swivel bracketTrimming is accomplished by the trim cylinders pushing on the swivel bracket at the thrust padsBy operating the electric switch in the "up" direction, the electric motor drives the hydraulic pump, forcing oil into the trim cylinders and the tilt cylinderBecause of mechanical and hydraulic advantage, the trim cylinders move the motor the first 15 of movement (Trim Range)The tilt cylinder moves the motor through the final 50 of motion (Tilt Range)The outboard can be operated while tilted past the initial 15 for shallow water driveAbove apprOXimately 1500 rpm, the trim up relief valve opens automatically lowering the motor to the fully trimmed out positionAttempts to tilt the motor when operating over 1500 rpm will have no effectOperation of the unit in the down direction is the opposite of movement in the up directionThe tilt cylinder moves first until the swivel bracket is resting on the trim rods which then begin to moveThe motor can be raised or lowered manually without electrical assistance using the manual release valve on the starboard side of the unitIt has screwdriver access through hole in the stern bracketSee Figure 9-1The slotted valve can be opened to allow oil to flow from one side of the tilt cylinder to the otherThe manual release valve effects tilt range only (not trim)